Testing a 5v power supply

[dougblair]

It would be good to know if there is a method of provoking the RPi  into using its max power ? I would guess it depends on how much it is processing.  I have a PAW supplied known good supply lead but would like to check my power supply on the ground before taking to the air. Sitting under the final approach to Heathrow for ADSB targets is a bit too far away.
Handheld and squelch knob will be emitted RF test. Any other suggestions ?

[JCurtis]

It would be good to know if there is a method of provoking the RPi  into using its max power ? I would guess it depends on how much it is processing.  I have a PAW supplied known good supply lead but would like to check my power supply on the ground before taking to the air. Sitting under the final approach to Heathrow for ADSB targets is a bit too far away.
Handheld and squelch knob will be emitted RF test. Any other suggestions ?

If you can power the PAW with everything connected, so ADBS antenna, bridge antenna, GPS, WiFi, and connect a tablet to it running your choice of Nav Software that would be enough.  Check the PAW screen to ensure the TX packet count is going up so the Bridge is running. 

Check the red power light on the Raspberry Pi stays fully lit all the times and doesn't flicker, if it does you could well have issues.

For radiated emissions you can use a handheld receiver/transceiver for a quick and dirty test, ideally check not just your local frequency but the whole band.  If you can set some presets then put some in spread throughout the 118.000 - 136.975 HMz range, if it scans have it scan those and if it stops as the squelch breaks that would give an indication.  Start with everything off and set the squelch to clear the background, have the radio no more than 1m from the PAW & power supply.  Just turn on the supply and run the scan, then connect the PAW and scan again.

If this is a supply rather than a power brick conducted emissions can be as big a problem (or worse) than radiated, but really to test that you'd need to be in the aircraft on the actual wiring to see the affects.  Testing this really needs the suitable equipment.

[dougblair]

Thanks, The quick and dirty test is really to stop me wasting time at the 35 mile away aircraft.  The first attempt was thwarted by the amount of RF noise from my Landrover Discovery 2. 12v battery now on charge for a cleaner test. The scan is a good idea.

[Admin]

Hi Doug

What you dont explain is what you are using to step down from 12v to 5v ?

Thx
Lee

[JCurtis]

Thanks, The quick and dirty test is really to stop me wasting time at the 35 mile away aircraft.  The first attempt was thwarted by the amount of RF noise from my Landrover Discovery 2. 12v battery now on charge for a cleaner test. The scan is a good idea.

Surprised by that, generally any reasonably modern vehicle is quiet(ish) RF wise these days.

[dougblair]

In Reply to LEE

I am using a cig lighter plug in 12-5v usb  convertor must be from China but looks reasonably well made.  I have a 12v cig lighter socket in the a/c and having removed the last of remnants of an ADF I have a switched audio feed that might work. I am keeping with the " portable " ethos for now.   I do have a good location for an external antenna if anyone has found a suitable device .

So far the power side has been OK using a decent USB lead.

 I like to have an idea that stuff will work before driving the 30 miles up to the aircraft usually having left the most important tool at home....................

[Admin]

Hi Doug,

In my experience, I have not had good experience with the USB 12-5v adapters from China.

If you are looking for a 12-5v converter, I have recently purchased an Anker 2 x 2.4A adapter which works really well and gives
me no radio interference I can detect.
The other issue to bear in mind is the quality of the power source can also affect the sensitivity of the P3I receiver, which you may not notice
simply by audio interference.

So I think the best choices right now are something like

Anker 12-5V Adapters
Anker power banks
Charge2
Charge4

Thx
Lee

[Paul_Sengupta]

One thing to try is to check the sensitivity of any radio receiver with the 12V/5V converter operating nearby. I noticed in my Jaguar that when I plugged in my phone to charge using a cheap Chinese converter next to the centre console where the car radio is installed, the radio reception got worse. There was no obvious "interference" received, but it was obviously affecting the radio. Moving it further away helped. But since then I've tested various adapters in the same way...firstly tuning to unused frequencies on MW and VHF to check for interference, then tuning to a very distant VHF radio station to see if the signal is degraded at all.

Obviously Jaguar radios aren't very well shielded, but the plus side is that they make good test kit!